Dart APIunself_local_databaseFieldCompanionid id property Null safety Value<String> id final Implementation final Value<String> id; unself_local_database unself_local_database FieldCompanion id property FieldCompanion class Constructors FieldCompanion insert Properties collectionId created extra hashCode id name required runtimeType system type unique updated Methods copyWith noSuchMethod toColumns toString Operators operator == Static methods custom